1. Field of the Invention
The present invention relates to an absorbent article such as a sanitary napkin, a disposable diaper or the like and, more particularly, to an absorbent article having longitudinally extending leakage preventing walls on the two sides.
2. Related Art
In the prior art, there have been developed a variety of absorbent articles including sanitary napkins, urine pads, disposable diapers and the like. These absorbent articles are demanded, when worn, to absorb a liquid waste reliably in a liquid-absorbent layer and to prevent the liquid waste from leaking to the outsides of the absorbent articles. Therefore, some absorbent article has longitudinally extending leakage preventing walls formed on the two sides on the liquid receiving face thereof.
Generally, the leakage preventing walls of the prior art are constructed such that unstretchable hydrophobic sheets extending in the longitudinal direction are joined to a surface sheet of an absorbent article and elastic members extending in the longitudinal direction of the absorbent article are joined to the hydrophobic sheets. By the longitudinal elastic shrinking forces of the elastic members, a longitudinally curving force is caused to act on the absorbent article, and the leakage preventing walls are raised on the liquid receiving side of the absorbent article so that the menstrual blood or the like can be prevented from leaking sideways.
In most of the leakage preventing walls of the absorbent article of the prior art, however, the surface to abut against the skin of a wearer is so flat that the leakage preventing walls come into contact with the skin of a wearer too tight. Moreover, most of them do not provide a soft contact with the skin due to its hard touch feel.
In some absorbent article of the prior art, on the other hand, the leakage preventing walls are formed of a nonwoven fabric which is deformed (formed) into a corrugated shape. The leakage preventing walls of this shape can reduce the contact area with the skin of a wearer so that they can provide a soft feel to the skin, as disclosed in International Unexamined Patent Publication No. 503934/1997, for example. However, since the leakage preventing walls of this disclosure are formed to exhibit the elastic force by themselves, the leakage preventing walls have a low rigidity of their own. Therefore, when the leakage preventing walls are disposed to rise from the surface of the absorbent article, for example, their buckling strength cannot be highly enhanced.
If longitudinally extending elastic members are joined to the nonwoven fabric deformed (or formed) into the corrugated shape, the resulting leakage preventing walls exhibit a high rising force from the liquid receiving side of the absorbent article, so that it becomes difficult for the leakage preventing walls to fall down. However, if these longitudinally extending elastic members are adhered to the corrugated nonwoven fabric with a hot-melt adhesive or the like, the crests of the corrugations are adhered with the adhesive when a pressing force acts on the nonwoven fabric. Therefore, the corrugations of the nonwoven fabric are liable to be kept in a crushed state. As a result, she nonwoven fabric is hardened at the portion where the elastic members are adhered, so that its contact feel with the skin of a wearer is deteriorated.
The present invention has an object to provide an absorbent article which can realize leakage preventing walls providing a soft touch to the skin of a wearer and which can prevent the adhered portion between the nonwoven fabric forming the leakage preventing wall and the elastic member from being hardened, thereby not to damage the soft feel.
According to an aspect of the invention, there is provided an absorbent article comprising: a main body including a liquid-permeable surface sheet disposed on its liquid receiving side, a back sheet, and an absorbent layer sandwiched between the surface sheet and the back sheet; and leakage preventing walls-disposed on the liquid receiving side-of the main body, the leakage preventing walls extending in a longitudinal direction of the article and lying opposite one another in a transverse direction perpendicular to the longitudinal direction,
wherein each leakage preventing wall is formed of a nonwoven fabric having corrugations, the crests and valleys of which alternate with each other in the longitudinal direction, the nonwoven fabric is provided with an elastic member extending in the longitudinal direction for exhibiting longitudinal shrinking force, and the elastic member is adhered to the valleys of the corrugations of the nonwoven fabric with an adhesive, which is applied to the surface of the elastic member in a band or linear shape continuous in the axial direction of the elastic member and appears regularly or at random at an interval on an arbitrary line which is set on the surface of the elastic member to extend parallel to the axial direction.
According to the absorbent article of the invention, the nonwoven fabric forming the leakage preventing wall is molded (or formed) to have the corrugations so that the contact area with the skin of a wearer can be reduced to eliminate the tightness on the skin and to soften the abutment. In addition, the elastic members for exhibiting the shrinking forces in the longitudinal direction are joined to the leakage preventing walls so that the longitudinal shrinking forces act on the leakage preventing walls. As a result, the absorbent article is longitudinally curved to allow the leakage preventing walls to rise easily. Moreover, since the applied adhesive appears intermittently on the arbitrary line extending in the longitudinal direction, the inner faces of the nonwoven fabric other than the valleys of the corrugations hardly contact with the adhesive. Accordingly, the corrugations of the nonwoven fabric are not either crushed or hardened with the adhesive even at the portion having the elastic member, to thereby prevent stiff contact feel with the skin of a wearer. Thus, the leakage preventing walls of the absorbent article can keep the soft feel.
For example, the adhesive may be applied to the surface of the elastic member along such an undulating locus that an amplitude is taken in a direction to intersect the longitudinal direction. Alternatively, the adhesive may be so applied to the surface of the elastic member as to form a helical locus which extends in the longitudinal direction while turning around the elastic member.
Preferably, the undulating locus or the helical locus of the adhesive has a period longer than that of the corrugations of the nonwoven fabric.
With the pitch (i.e., period) of the corrugations of the nonwoven fabric being made small, in the absorbent article of the invention, the leakage preventing walls can be made soft not only in their structure but also in their abutment against the skin of a wearer. In this case, if the period of the undulating locus or the helical locus of the applied adhesive is made longer than that of the corrugations of the nonwoven fabric, the probability for the portions of the nonwoven fabric other than the valleys of the corrugations to come into contact with the adhesive can be lowered to enhance the corrugation crush preventing effect. On the other hand, the individual valleys of the corrugations of the nonwoven fabric can be adhered highly probability to the elastic members with the adhesive.
Preferably, the nonwoven fabric is folded back at the free end of the leakage preventing wall so that the leakage preventing wall is formed of the two-folded nonwoven fabric, and the elastic member is positioned between the two-folded nonwoven fabric so that the valleys of the corrugations of the nonwoven fabric are positioned on two sides of the elastic member and are individually adhered to the elastic member with the adhesive.
In the invention, however, it may also be possible that the nonwoven fabric is not folded back at the free end of the leakage preventing wall and that the valleys of the corrugations of the nonwoven fabric are positioned on and adhered to only one side of the elastic member.